Refrigerating apparatus



G. C. PEARCE nammnaurme APPARATUS Jan. 21, 1941,

4 Sheets-Sheet 1 Filed April 28, 1958 IN VENT OR.

Jan. 21, 1941.

G. C. PEARCE ummsmvrme Arrm'rus Filed April 28, 1938 4 Sheets-Sheet 2mvgmon B W ATTORNEYS I L a 95 .2

9 G. c. PEARCE 2,229,612

REFRIGBRATING APPARATUS Filed April 28, 1936 4 Sheets-Sheet :5

10", II I I.

- Jan. 21, 1941. c, PEARCE 2,229,612

RBFHIGERATING APPARATUS I Filed April 28, 1938 4'Sheets-Sheefc4 PatentedJan. 21, 1941 APPARATUS George Pearce, Dayton, Ohio, assitno'r toGeneral Motors Corporation, Dayton, Ohio, a corporation of DelawareApplication April 28, 1938, serial No. 204,796

16 Claims. (01.23644) 1 This invention relatestp refrigerating apparatusand more particularly to control systems and control means for heatingand cooling apparatus.

It is an object of my invention to provide an improved control systemfor heating and cooling apparatus requiring one only room thermostat.

It is another object of my invention to provide an improved controlsystem for heating and cooling apparatus in which means are provided forautomatically changing the control from the heating apparatus to thecooling apparatus and vice versa at the proper time.

It is another object of my invention to provide an improved andsimplified form of eifective temperature control.

It is another object of my invention to provide an improved reliablesimple form of a room thermostat which is economical to manufacture,which is conveniently adjustable and which can operate at full or lesservoltages.

It is-ancther object of my invention to provide a room thermostat whichis small, compact and yet has all its parts readily accessible.

It is still another object of my invention to provide an improved formof room thermostat in which pivot pins and other sources of friction thecontacts with sufllcient rapidity to avoid arc- Fig. l is a diagrammaticview of an effective temperature control system for heating and cool ingapparatus embodying one form of my invention; I

Fig. 2 is a vertical sectional view through a .form of room thermostatembodying my invenof thermostat embodying my invention;

Fig. 6 is a section taken along the lines 6-6 of F18. 4;

Fig. 7 is a section taken along the lines 1-1 Fie. 2; Y

Fig. 8-is an elevational view of another form 5 of thermostat embodyingmy invention;

Fig. 9 is an elevational view of still another form of a thermostatembodying my invention;

Fig. 10 is a view in elevation of another form 10 Fig. 11 is an end viewof the thermostat shown in Fig. 10; and

Fig. 12 is a view in elevation of still another form of thermostatshowing my invention.

the snap acting type controlled by outside temperature changes thecontrol from the heating apparatus to the cooling apparatus and viceversa 'when the outdoor temperature rises above or falls below certainpredetermined temperatures 2! for which the switch is set. With thisarrangement only one room thermostat is required for the control oftheheating and cooling apparatus, l

The effective temperature control incorporates 80 a plurality of bimetalelements arranged in cantilever fashion which are critically stressed bya tension coil spring which causes the bimetal elements to snap from onelimiting position to the other. The temperature at whichthe bimetalelements snap is controlled by the adjustment of the anchoring point ofthe spring which has its other end connected to the free end of thebimetal elements. This-general form of snap acting control mechanism isfound in substantially all the modifications shown in this application.

FIGURE 1 Referring now to the drawings and more particularly Fig. 1,there is indicated diagrammatically an enclosure 20 containing a heatingapparatus 22 shown as an electric motor which may be used to operate anoil burner or a stoker, and at the side of the motor 22 is anotherelectric motor 24 which may be used, to operate a refriger- 5o atingsystem for cooling'the enclosure. The system is provided with' powerthrough the electrical conductors 26 and 28 which supply electric energyto the transformer 30 which in'turn supplies electric energy at thereducedvoltage to the ccn- 5 trol circuit, which includes the conductor32, the effective temperature control switch 34, the conductor 36, thetwo-way relay 38 and the conductor 40. The conductor 28 is connected bythe conductor 42 which includes manually operable switch 44 to thesnapacting switch means 48 operated by a bellows 48.

This bellows 48 is connected by a small tube 50 to a thermostatbulb 52located outside the enclosure 20, so that it is subjected to thetemperature of the outside air. The snap acting switch means 48 includesa bimetal blade 54 mounted at an intermediate point upon a post 56 andhaving a tension type coil spring 58 connected to the blade adjacent itsopposite ends.-

The bellows 48 is provided with astem 80 which bears upon the short endportion of the blade 54 while the other endof the blade is provided withdouble contacts 82 which are adapted to contact with the stationarycontacts 84 and 88. The range of the switch is controlled by acompression type spring 88 which opposes the expansion of the bellows 48and which has its tension controlled by .the adjusting screw I0.

The contact 84 is connected by the conductor I2, which includes a manualswitch I4, to a stationary contact I8 engaged by relay contact bar I8which closes the circuit to the heating motor 22 'by carrying thecurrent to the other upper stationary contact 80, which is connected bythe conductor 82 to the motor 22. The stationary contact 88 is.connected by conductor 84 provided with a manual switch 88 to thecontact 88 which is one of the lower stationary contacts for the relay38. The relay 38 has a lower- 'rigid contact bar 90 which engages andbridges the lower stationary contact 88 and the second, lowerstatic-nary contact 92 for controlling the flow of electric energy tothe conductor 84 which connects to the cooling motor 24. In order tocomplete the electric circuit, the electric motors 22 and 24 are eachconnected to the common conductor 98 which connects to the conductor 28which serves as the second supply conductor, as mentioned before.

The efiectioe temperature control The effective temperature controlincludes a base I02 upon which is mounted a-post I04 carrying acantilever bimetal blade I08 of resilient bimetal at its upper end, anda second resilient cantilever bimetal member I08 adjacent its lower endwhich is substantially identical to the bimetal member I08. The freeends of the'bimetal" members I08 and I08 extend into notches formed inthe cross-arms of a cross-shaped member IIO. This cross-shaped member Hhas its notches spaced a distance equal to the spacing of the membersI08 and I08 upon the tension I04. The cross-shaped member H0 is held inengagement with the free end of members I08 and I08 by a tension typecoil spring II2 which extends substantially in the same direction asbimetal members I08 and I08 to an anchorage H4 located,beyond the postupon a vertical adjusting screw H8.

The anchorage H4 is in,the form of a small fiat piece of. metal which iswelded or soldered to a nut which is threaded onto the adjusting screw II8. The upper end of the adjusting screw I I8 is rotatably mounted in anaperture provided in the sheet metal arm I I8 extending from the baseI04 and fastened to the post I04 by a screw I20. The upper end of theadjusting screw 4 I8 is provided with a nut I22 resting upon the armII8. so that it rotates with the adjusting screw II8 when the adjustingscrew is turned to move the anchorage H4 upwardly or downwardly tochange the position of the anchoring point of the tension spring I I 2.

The coil spring II2 has such a tensionas to provide a critical load uponthe ends of the bimetal members I08 and I08. The movement 'of thebimetal members I08 and I08 is limited by the nuts I24 and I28 whichengage the long leg of the cross-shaped member IIO to limit itsmovement. These nuts I24 and I28 are threaded onto a screw I28 which isfastened to and projects upwardly from the base I02.

A stationary contact I30 is provided upon the bottom of the base I02 andis connected by a This nut I22 is soldered to the post I02 conductor tothe heater I32 which is connected in series with the contacts and isemployed for overcoming a portion of the differential of the switch,particularly for the purpose of compensating for the lag in the heatingsystem. The movable contact I34 is provided upon the spring metal memberI38 which is fastened to the bottom of the base I02 by a screw I38 whichis connected to the conductor 32. The spring member I38 is arranged incantilever fashion and has an upwardly projecting arm I40 beyond thecontact I34 which extends through the base and is located in the path ofmovement of the bimetal strip I 08. This spring member I38 is normallysprung upwardly with sufilcient tension to provide satisfactory contactpressure between the contacts I30 and I34.

The humidity element Thus far the control described constitutes athermostat switch of a peculiar double bimetal type. In order to makethis an efiective tem-, perature control I suspend an element 4 from theend of the long cross-arm of the crossshaped member I I0 by means of awire threaded their weight varies with the amount'of humidity in theair. This weight is added to the force upon the bimetal members I08 andI 08 so that the bimetals are influenced by the humidityoi the air aswell as by the temperature of the air.

The element I44 should have such a surface and .such an amount ofsolution that it will influence the bimetals in such a proportion to theinfluence .of tempera ure upon the bimetals so as to make the controlresponsive to the effective temperature of the air rather than solely tothe dry bulb.

temperature. V

When the outside air temperature is cold, the

switch 48'is in the position shown in the figure so that current flowsi'rom the conductor 28 through the conductor 42, the plate 54, thecontacts 82 and 84 and the conductor I2 to the upper If the stationarycontact I8 of the relay 38. effective temperature of the air is such asto require more heat, for example, if the humidity is average and thetemperature is below F. the switch 34 willbe closedj thus closing thecontrol circuit and energizing the relay 38 to cause the contact bar I8to bridge the contacts I8 and 88 and cause current to flow to theheatingmotor 22, which will operate to supply heat to the enclosure 20. Theanticipating heater I32 will then be in operation and a small increasein temperature of the enclosure 20 will cause the switch 34 to beopened. This will deenergize the relay 38 and causethe contact bar 18 todrop to open position. i

This will stop the heating system and the heating system will remainidle until the eflective temperature again falls suiilciently to causethe bimetal elements I06 and I08 to move to their upper position inwhich the contacts I30 and I34 are sprung closed. It should be notedthat when the heating system is idle the contact bar 88 engages thecontacts 88 and 82. However, since the contact 62 is out of engagementwith the contact.

. 66 no current flows to the cooling motor 24.

However, should the outside temperature rise to about 75 or 80 F. theswitch 46 will be actuated and the expansion of the volatile fluid. inthe bellows 48 will cause the blade 64 to be snapped to its otherposition in which the contact 62 is inengagement with the contact 66.Under this condition when the temperature is below normal the contactsI30 and I34 will be closed asbefore. This will causethe relay 38 to beenergized thus raising the contact bar 88 away from the contacts 88 and82 so that no current will be supplied to the cooling motor 24. Shouldthe temperature within the enclosure 28 rise, the contacts I30 and I34will be opened by the-effective temperature control 34. This willdeenergize the relay 38 and cause the contact bar 86 to bridge thecontacts 88 and 82 to supply the motor 24 with electric energy to coolthe enclosure 20. As long as the 8: master switch 46 has the contacts 62in engagement with the contact 66 no current can be supplied to theheating motor 22.

Should the outside temperature fall to 70 or '75 F. the switch 46 willagain move to the posij tion shown in Fig. 1 so that heating may againbe obtained. If either heating or cooling is not desired either of theswitches 14 or 86 may be opened.

FIGURES 2 r0 7 In Figs. 2 to 7 inclusive there is shown a com mercialform of my improved type of bimetal control. This is shown in the formof a wall thermostat and is provided with a base 202 of a moldedelectrical insulating material which is adapted to be fastened tothewall. Openings 204 and 206 are provided in the base for this purpose.This base 202 is provided with an opening 288 through which connections.may be made to the electric wiring in the walls of the building. Asshown in Fig. 4 the electrical conductors 2III and 2I2 are fastened-tothe binding screws 2". These binding screws are electrically connectedto spring metal members '2I6 and 2I8 which are fastened to the base. byrivets. The base is also provided with a pin 228 at the top whichreceives the aperture in the top of the cover 222 which encloses, theswitch mechanism. The bottom of the cover 222 is firmly held in place bya fastening screw-224 which is threaded through the bottom of the outercover into a rim portion of the base. This cover is removable from thebase as is the switch mechanismproper. a

The switch mechanism proper is mounted upon a metal plate 228 which isseparated from the base by insulating material 228 of slightly greaterthickness. These pieces 226 and 228 are fastened .to the base by screws238; The metal plate 226 has riveted to it, on the face provided withthe insulating sheet 228, an assembly which includes jects.

through the hollow post 214' into contact with an insulating member 232,a bent metal'blade 234 forming a stationary contact blade, anotherinsulating member 236 and a second movable contact blade 238. Thisassembly is riveted to the metal base 226 by rivets 242. The contactblades 234 and 238 are kept separate and insulated-from each other 'bythe insulating piece 236. The contact blade 2| 6 makes contact with ascrew 244 which is screwed into a small plate which in turn is fastenedto the blade 238. 10 A screw 246 is fastened to a metal arm 248 whichcarries the conductor provided at one end of the carbon type heater 260while the conductor at the other end of the carbon type heater isfastened to the arm 262 which is held in place by the screw 254. Themetal plate 226, the sheet of insulation 228 and the two pieces 0!insulation 232 and 236 are all provided with an aperture 286 throughwhich the carbon type. heater 250 pro- This opening is covered byanother thin piece of insulation 258 so that a well insulatedcompartment is provided between the sheet metal The blade 238 isprovided with a movable con- 25 I tact 260 while the stationary contact262 is provided upon the blade 234. The blade 234 is provided with aset-screw 264 which adjusts its position with reference to the plate226.

The plate 226 has a pair of main posts 266 riveted to it and these mainposts at their upper ends have a bimetal blade 268 riveted to them andextending therefrom in two directions. Also riveted to the outer ends ofthe posts 266 over the bimetal blade 268 is a supporting member 210 '35which is supported at the other end by a high post 212 which extends toand is riveted to the metal plate 226. -The longer portion of thebimetal blade 268 extends upwardly and operates between the end of ahollow post 214 and an adjusting nut (01 216 which is threaded onto thescrew 218 which is riveted to the. plate 226. The blade has its upperend stiffened by the inverted U-shaped rib 280. which is pressed intoit. This inverted U-- shaped rib stiflens the end of the blade'and tends45 to prevent the upper portion of the blade from assuming an s shape.This ribbing stifiens the upper third of the portion of the blade abovethe posts 266. The remaining portionof the blade between the ribbedportion 288 and the posts 2661s provided with a central slot 282 'toprevent the blade from being too s'tifl under certain temperatureconditions.

The upper end of the blade is adapted to operate an insulating pin 284which extends the upper extension 286 of the blade 238. The pin 284should be somewhat'shorter than the distancebetween the extendingportion 286 of the contact blade 238 and the upper portion of thebimetal 268 when it is against the stop nut 216. It, however, should belonger. than the distance between these blades when the upper end of thebimetal is against the hollow stop member 214 so that the contacts 268and 262 may be separated. The set-screw 264 may be adjusted to vary theamount of separation provided for the contacts. The nut 216 maybeadjusted closer or further away from the. post 214 ,to decrease orincrease the differential of the switch. 70

The other end of the bimetal 268 is bent slightly below the posts 266toward the plate 226. This causes this portion of the'blade to restagainst the wings 280 upon an adjusting member 282 which has a tongue284 extending between; and u guided by the posts 266-. The portion ofthe adjusting member 292. between the wing portions 290 is extruded andthreaded so as to receive the threaded portion of the main adjustingscrew 296. This main adjusting screw'is hollow and has another screw 298extending through it which is threaded into a metal portion 302 which ismolded into the temperature control knob 304. This temperature controlknob is preferably made of some suitable ornamental plastic and hasfigures and marks molded therein to indicate different temperaturesettings. The hollow screw 296 is locked to the knob 304 solely by thefriction between the metal insert 302 and the head of the screw 296. Thescrew 298 is tightened sumciently so that this friction is great enoughthat there will be no slippage between the knob and the screw 296. Bysuch a connection any desired relation between the knob and the hollowscrew may be made by loosening the inner screw 298, turning the knobrelative to the hollow screw and again tightening the inner screw 298.

The bimetal blade 268' is provided with ears at its extreme four cornerswhich are connected by tension coil springs 306, 308, 3I0 and M2 and thethreaded connectors 3l4 and 3l6. In Fig. 2 the greater portion of thesprings 306 and 308 are broken away and the connector 3 has been removedin order to better show the construction of the switch. The connectors 3and 3l6 serve as'an adjustment for the tension of the springs 50' thatthe springs may be set to the particular tension which is required tocritically load the upper end of the bimetal 268 so that it will movefrom either of its stopsto the other with a snap action.

In this modification only the portion of the bimetal blade 268 above theposts 266 is active and it is really only the portion between theseposts and the riveted portion that is fully active. The portion belowthe posts which rests against the wings 290 and the adjusting member 292is used solely for the purpose of adjusting the anchor point of thelower ends of the spring means. By turning knob 304, the. bent lower endof the bimetal member 268 is moved toward or away from the plate 226 inorder to change the temperature at which the upper portion of thebimetal 268 snaps from one limit of movementto the other. Thisform ofadjustment provides a relatively wide range of temperature selectionwith accuracy, and it does it in a very simple manner. 'The adjustingknob 304 is provided with a rib 320 which is adapted to be stopped by apost 322 which is riveted upon the metal support member 210 which servesas the outer bearing for hollow screw 296 while the metal plate 226serves as the inner bearing for the hollow screw.

As mentioned before, the entire switch mechanism is mounted upon andremovable with the metal plate 226. The removal of this switch mechanismmakes accessible the binding screws 2 to which the'control wires may befastened.

The'outer cover is, of course, also removable and carries a mercury typethermometer 324 which is backed by metal supporting means 326- which isheld at its upper end by tongues 328 which are bent downwardly from theopenings 350 provided in the top of the outer case 222. The lower end oithe metal supporting means 326 for the thermometer 324 is fastened by ascrew 328 which threads into a post 330 fastened-.to the inner face ofthe cup. i Fig. 4 shows the connection of this control to a heatingmeans which includes an electric motor 332 for driving a stoker or oilburner. This motor 332 is controlled by a relay 334 which is connectedin. series with the conductors 2I0 and H2 connecting to the thermostatcontrol through the opening 208 in the base 202. The conductors 2H) and2l2 are connected to the same power lines with which the motor 332 issupplied and operated with the same voltage as the motor 332. The motor332 may also be used to drive refrigerating apparatus for coolingpurposes and in this event the only change that need be made is toreverse the bimetal 268 and to bend the lower portion of the bimetalbelow the posts 266 toward the metal plates 226 so that the bimetal,engages the wings 290 of the adjusting member 292. With thisconstruction the switch may operate at the same voltage carried by a.motor 332 with full speed. The bottom portion and the cover is providedwith ventilating openings 336 so that the portion of the controlcontaining the bimetal 268 may be adequately ventilated.

When using'the control for a refrigerating system the anticipatingheater 250 must be omitted and a connection must be made from the screw246 to the fixed blade 234. If it is desired to use an anticipatingheater for controlling cooling, a high resistance heater must be usedand the upper arm corresponding to the arm 252 of the heater should be.connectedto the screw 244 or the rivet just above the screw 244. Inthis way this control is easily adapted for either heating or coolingthe control. If it is desired to use this as an effectivetemperature'control a humidity element such as the element shown in Fig.1, may be used and connected to the upper end of the .bimetal plate 268so-that it will tend to pull the bimetal blade away from the contactswhen used for heating and toward the contacts when used 7 forcontrolling cooling.

' FIGURE 8 In Fig. 8 there is shown a pressure-operated form of switchin which this same type of conported by the base and is connected to athermostatic bulb by a tube M0. The upper end of the bellows is providedwith a conical point 4 I 2 which engages the short end of the strip 402.The long end of the metal strip 402 is provided with a contact 4 adaptedto engage a spring mounted contact 6 mounted upon the free end of theleaf spring member 8 fastened to the base 406. The free ,end of theblade 402 is limited in its movement by the nuts 420 and 422 which arethreaded upon the screw 424 fastened to the base. The short end of theblade 402 held against the, upper conicalpoint 2 by a tension type coilspring 426 which is fastened at its lower end to an adjusting screw 428for adjusting the range or the switch while the differential is adjustedby the nuts 420 .and 422. This construction provides a very simplepressure-operated switch with friction reduced to a very low value.

FIGURE 9 base by the rivets 436'. The end of the bimetal member 434which rests on top of the base 492 tends in the same direction as thebimetal 484.

This bimetal blade 439 is free to move to 'a limited extent at the endadjacent the rivet 436 where a screw 440 is provided. This screw 445 isfastened to the base and provided with the nut's 442 and 444 which limitthe movement of the free end of the bimetal blade 439.

The free end of the bimetal blade 439 has tension type coil spring 449connected to it and extending toward the post 432. The post 432 has aU-shaped metal member 448 fastened to and extending in an oppositedirection from the bimetal members. This U-shaped memberhas the otherend of the tension spring 448 fastened to it. This metal member 449 maybe moved toward or away from the base 430 by the adjust-' ing screw 450for changing the anchoring point of the spring 446 in order to changethe temperature at which the bimetal blade 439 is snapped from onestopscrew-to'the other. A spring 4.52 holds the metal member 449 in contactwith the head of the screw 450 while the bottom of the screw 45! isthreaded into the base which is provided with a nut 454 held firm y bythe base.

The spring 446 is provided. with sufficient tension as to impose acritical load upon the bimetal olade 439 ,so as to cause it to snap fromone stop nut to the other. The free end of the blade 438- is adapted tostrike an upwardly extending portion 456 of a spring contact support 459which is fastened to the baseby the rivet 460. This spring contactmember [15 normally sprung to contact closed position with sumcientforceto provide satisfactory contact pressure. member 459 is provided with-amovable contact 492 which is adapted to make contact with the stationarycontact 454. It will be seen that this form of control may be madeshorter than the other embodiments because the curling of the bimetalblade 448 due to temperature is aug-- mented by the curling of thebimetal blade 414- also due to temperature. If desired a double set ofblades side by side may be employed or a double set of springs may beemployed.

. 7 Frame 10 small In Figs. 10 and 11 still'another form of control isshown in which there is provided a lower base 415 and an upper base 412held in spaced relation by the posts 414and 419. The lower base 419 isprovided with -a post 419 which supports one end of the cantilever typebimetal blade 4. The free end of this cantilever bimetal blade 4" isprovided with a permanent magnet 482 and a contact supporting springmember 494 which supports a contact-.485. The upper base"! is providedwith a post 499. Resting against this post but not fastened to it is oneend of a bent spring metal member 499 havin a greater portion of itsother end fastened to the upper base 412. Immediately beneath thismember 499 is an adjusting member 492 which is fastened to the member499 and to an upper cantilever bimetal blade 494. An adjusting screw 49.rotatably mounted in the upper base 412 pulls the adjusting member 492upwardly or downwardly against the .tension of the spring member 499which has a tendencyto turn the for supporting the' armature, eachsupporting a contact, I have provided a more sensitive switch and inaddition, whenever the switch is subject to vibration the vibration willaffect each about equally.

FIGURE 12 In Fig: 12 there is shown another double bimetal controlsimilar to the effective temperature control shown in Fig. 1. In thiscontrol the base 5! is provided with the post BIZ which supports one endof the spaced cantilever bimetal blades 5l4 and SIB. The other free endof these bimetal blades is received within notches formed in the arm ofa cross-shaped member 519 having one arm operating between thedifferential-adjusting nuts 520 and 522 which are threaded upon thescrew 524 extending upwardly from the base 5I0; These nuts 52!! and 522limit the movement of the cross-shaped member H8 and thereby limit themovement of the free end of the spaced parallel bimetal blades H4 and519.

A stationary contact 526 is fastened to the base 5N as is one end of aspring contact support 529 which has its other end hooked over the freeend of the lower bimetal blade 5. This spring contact support isprovided with a movable contact 590, and a spring contact support 528 isprovided with a sufficient spring force to normally hold the contacts530 and 519 in contact with each other with suflicient contact pressure.A tension type coil spring 532 is connected to the arm of thecross-shaped member- 5l8 between the free ends of the blades H4 and 516for holding the cross-shaped member 5" into contact with the ends of theblades and also for providing a critical'load upon the free end of thebimetal blades. The other end of the 'spring 532 is hooked onto theadjusting member 534 which is threaded onto the adjusting screw 535which is rotatably mounted in the base 5III and is sup-'- I ported by ametal member 538 extending from bimetal strip, in cantilever fashion,spring means having one and connected to the strip at a point remotefrom its supporting point, an anchorage .for.the otherendof said springmeans located adjacent the suppgrt for the strip, said spring meansexerting its major component of force along said bimetal trip toward itspoint of support,'a control means operated by the movement of saidbimetal stripjand means for adjusting in a direction substantiallyperpendicularly to said bimetal strip the anchorage for said springmeans forchanging the temperatures at which the bimetal strip operates.

2. A thermostatic control comprising a resilient bimetal strip, meansfor supporting the bimetal strip in cantilever fashion, a tension typespring means having one end connected to the strip at a point remotefrom its supporting point, an anchorage for the other end of said springmeans, said spring means exerting its major component of force alongsaid bimetal strip toward its point of support, a control means operingthe temperatures at which the bimetal strip ing the movement of saidbimetal strip, said a having one end'connected to the strip at a pointremote from its supporting 'point, an anchorage for the other end ofsaid spring means, said springmeans exerting its major component offorce along said bimetal strip toward its pointof support, a controlmeans operated by the movement or said bimetal strip, meansforlimitspring means being provided with a tension sufflcient to causethe bimetal strip to snap from one limit of movement to another,adjusting means for, moving said anchorage substantially perpendicularlyto saidbimetal strip vfor changing the temperatures at which the,bimetal strip I snaps from one limit of movement to the other, and asecond adjusting means for adjusting the tension of said spring means inthe direction of its axis.

4. A thermostatic control comprising a resilient bimetal strip, means'for supporting said strip in cantilever fashion, spring means havingits axis extending substantially in alignment with said bimetal strip,said spring means being connected at one end to said bimetal strip at apoint remote from its support, an anchorage for the other end of saidspring means located adjacent the support for the strip, a control meansoperated by the movement of said bimetal strip, and means for adjustingsaid anchorage generally perpendicularly to said bimetal strip, foradjusting the temperatures at which the strip operates the controlmeans. s

5. A thermostatic control comprising a gen- I 'erally straight resilientbimetal strip, means for ity for exerting a force generally in a lateraldi-' rection directly upon the resilient cantilever arm portion of saidbimetal strip.

' ,8. A thermostatic control comprising a resil- 7 ient bimetal strip,means for supporting said strip in cantilever fashion, spring meanshaving its axis extending substantially in alignment with said bimetalstrip, said spring means being connected at one end to said bimetalstrip at a point remote from its support, an anchorage for the other endof said spring means, a control means operated by the movement of saidbimetalstrip, and means including a suspended member capable ofabsorbing and expelling moisture according to changes in humidity of thesurrounding atmosphere for exerting a force in accordance with itsweight upon said bimetal strip in its normal direction of movement.

7. A temperature control comprising a resilient bimetal strip, means forsupporting said strip in cantilever fashion including a stationaryanchorage ior immovably anchoring one portion of said strip, a controlmeans operated by the movement of said strip, and means including anelement whose weight changes with changes in humidity for exerting aforce in accordance with its weight upon the resilient cantilever armportion of said bimetal strip in the normal direction of movement ofsaid strip.

8. A temperature control comprising a thin resilient metal strip, meansfor supporting said strip intermediate the ends thereof, spring meanshaving the ends connected to said strip upon opposite sides of thesupporting means, a control means operated by a portion or the strip onone side,ot the supporting .means, and means for moving a portion ofsaid strip upon the other of the strip operated by the control means tosnap from one limit of movement to'the other,

and means for moving said strip to cause it to snap from one position toanother to operate the control means.

10. A thermostatic control comprising a resilient bimetal strip, meansfor supporting the bimetal strip in cantilever fashion, spring meanshaving one-end connected to the strip at a point remote from itssupporting point for applying a critical column loading to said strip,an anchorage for the other end of said spring means, said spring meansexerting its major component 01 force along said bimetal strip towardits point of support, a control means operated by the movement of saidbimetal strip, and means for adjusting in a direction substantiallyperpendicularly to said bimetal strip the anchorage for said springmeans for changing the temperatures at which the bimetal strip operates.

11. A switch mechanismincluding a movable member, contact means operatedby said movable member including a plurality of spring sections 76anaemia having their adjacent end portions threaded onto a threadedmember. r

13. A thermostat control comprising a plurality 01' generally parallelresilient strips, one of said strips being formed of bimetal. means (orsupporting said strips in cantilever fashion.

means for connecting the free ends of said strips to cause them tooperate together, a control means operated by the movement of one orsaid strips, spring means acting upon said connecting means and exertingits major component of iorce parallel to said resilient strips towardtheir points support for applying a critical column loading to each ofthe strips, said spring means being provided with a tension suflicientto cause the strips to snap from one position to another.

14. A thermostat control comprising a generally horizontal resilientbimetal strip, stationary anchorage means for immovably supporting oneportion of the strip, a member capable oi-absorbing and expellingmoisture according to movably anchoring one of said strip, a

member capable oi absorbing and expelling moisture according to changesin humidity oi the surrounding atmosphere. said member having its weightsupported by the free end oi said strip for deflecting with respect toits anchorage the free end according to its weight,'spring meansconnected to the free end of said strip and exerting the major componentof its force alon 1 thestripin the direction of its support forapplyinga critical column loading to said strip, and control meansoperated by the deflection of the free end 0! said strip.

l6. A'thermostatic control comprising a resilicnt bimetai strip, meansfor supporting said strip in cantilever fashion including stationaryanchorage means for immovably anchoring one strip, said spring meansbeing connected at one end to said bimetal strip at a point removed fromits support for applying a critical column loading to said strip, ananchorage tor the other end of said spring means, a control meansoperated by the movement oi! said bimetal'strlp, and means including asuspended member capable of absorbing and expelling moisture accordingto changes in humidity of the surrounding atmosphere for exerting aforce in accordance with its weight directly upon the resilientcantilever arm portion of said bimetal strip to deflect the strip withrespect to its anchorage in its normal direction of movement.

ononqn c. PEARCE,

portion or said strip, spring means having its axis extendingsubstantially parallel to said bimetai

